He either shopped it or hinted at confirmation to Tim Russert, Matt Cooper, and Judy Miller.
Whether he "shopped" it or not has no affect on his conviction. The misleading part of his cooperation with the investigation was his claim that he didn't know, except from reporters, that Wilson's wife worked at the CIA.
Russert told an FBI agent that they didn't discuss Plame at all. The agent testified to this effect during the trial, as Russert had passed away.
Judy Miller testified that her notes from an intervew with Libby simply said that "Wilson's wife may have worked on unconventional weapons at the CIA". He didn't identify her by name, and didn't say anything about her covert status.
Matthew Cooper actually asked Libby "If he had heard anything about Wilson's wife sending her husband to Niger", and Libby reportedly responded to the effect of: "Yeah, I've heard that too". He said nothing about her covert status or even working for the CIA.
The misleading part of his cooperation with the investigation was his claim that he didn't know, except from reporters, that Wilson's wife worked at the CIA.
Libby doesn't dispute that that he first learned about it from Cheney -- he testified that he realized it later. The question is whether he intentionally concealed it at the time of the investigation and grand jury testimony.
My problem with all of this is that Libby apparently didn't even know Plame was a covert agent. So, like Armitrage, there was no crime committed other than his recollection about the order in which things occurred.
Fitzgerald knew the source of the leak right away. So, why was he so intent on getting some conviction?